Thiol-Terminated Diene Polymers With Lower Chain Coupling
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Solution Overview
Problem
Existing methods for producing diene polymers with thiol end groups are inefficient due to high degree of chain coupling, which reduces the number of thiol-functionalized polymer chain-ends and requires additional steps to remove undesired trialkyl silanols, making them uneconomical.
Innovation Solution
A process involving anionic polymerization followed by sequential reaction with specific cyclosiloxane and thia-silacyclobutane functionalization reagents to produce diene polymers with thiol or thiolate end groups, optimizing end-group functionalization and reducing chain coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If 1-thia-2-silocyclopentanes are used to functionalize polymer ends, then thiol end groups are generated, but the degree of chain coupling becomes high which reduces the number of thiol-functionalized polymer chain-ends
Solution Approach 1:
The patent extracts and removes the problematic silicon atom from the functionalization reagent structure. By using thia-silacyclobutane (a four-membered ring containing sulfur and silicon) instead of 1-thia-2-silocyclopentane (a five-membered ring), the reagent delivers the thiol group to the polymer chain end while the silicon byproduct can be more easily removed, thereby reducing chain coupling and increasing the number of thiol-functionalized chain ends.
Solution Approach 2:
The patent changes the structural parameters of the functionalization reagent by reducing the ring size from five-membered (1-thia-2-silocyclopentane) to four-membered (thia-silacyclobutane). This parameter change in the reagent structure leads to improved reaction outcomes with lower chain coupling and higher yield of thiol-functionalized polymer chain ends.
2Quantity of substance
If protective —SiR3 groups are cleaved off to generate free thiol end groups, then thiol end groups are obtained, but trialkyl silanols are generated as undesired byproducts requiring additional removal steps
Solution Approach 1:
The patent extracts and eliminates the formation of trialkyl silanol byproducts by using a different functionalization reagent (thia-silacyclobutane instead of silane-sulfide with protective groups). This direct functionalization approach delivers thiol groups without generating the harmful trialkyl silanol byproducts that would require additional removal steps.
Solution Approach 2:
The patent converts the potentially harmful silicon-containing byproducts into a manageable form by using thia-silacyclobutane, which produces smaller, more easily removable silane byproducts. This transforms the harmful effect of silicon byproduct formation into a beneficial situation where the byproducts can be more easily eliminated without additional complex processing steps.
3Manufacturing precision
If additional process steps are added to remove trialkyl silanols, then purity is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for additional purification steps by using thia-silacyclobutane as the functionalization reagent. This reagent produces byproducts that do not require additional removal steps, thereby maintaining high purity while reducing manufacturing complexity and eliminating uneconomical process steps.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process enhances the production of diene polymers with improved dynamic mechanical properties, increasing the number of thiol-terminated polymer chains and simplifying the manufacturing process by eliminating the need for additional removal steps, thereby improving the efficiency and cost-effectiveness of the polymer production.
Implementation Method 1
preparing a diene polymer by a polymerization reaction that produces anionic chain ends
Implementation Method 2
reacting the at least one first functionalisation reagent with the anionic chain ends of the diene polymer to obtain a first reaction product
Implementation Method 3
adding at least one second functionalising reagent (IV) to the first reaction product to produce a thiol-terminated or thiolate-terminated diene polymer
Data Source
AI summary
A process for making a functionalized diene polymer terminated by a functional end group selected from thiol containing end groups, thiolate containing end groups and a combination thereof, comprising(i) preparing a diene polymer by a polymerization reaction comprising an anionic polymerization reaction;(ii) adding at least one first functionalisation reagent according to formula (III) to the polymerization reaction and reacting the at least one first functionalisation reagent with the anionic chain ends of the diene polymer to obtain a first reaction product,(iii) adding at least one second functionalising reagent (IV) to the first reaction product to produce a thiol-terminated or thiolate-terminated diene polymer; wherein the process, optionally, further comprises(iv) isolating the thiol-terminated or thiolate-terminated diene polymer from the reaction mixture, and optionally further comprising(v) bringing the diene polymer into the form of sheets, bales, granules, bales or into the form of a powder,wherein the thiol-terminated or thiolate-terminated diene polymer contains at least 51% by weight based on the total weight of the polymer of units derived from 1,3-butadiene, and wherein in formula (III) and (IV) R1, R2, R3 and R4 represent, independently from each other, hydrogen or a hydrocarbon residue containing from 1 to 24 carbon atoms per unit n and wherein the hydrocarbon residue may be saturated or may contain at least one carbon-carbon double bond and wherein the hydrocarbon residue may be interrupted once or more than once by O, Si or S atoms and may contain one or more substituents selected from alkyl amino, alkyl phosphino, alkyl silyl substituents and combinations thereof;R5 represents an alkylene group —[CXY]p— wherein p is an integer selected from 2, 3, 4 or 5 and X and Y are independent from each other selected from H, or C1-C6 alkyl and each X and Y may be the same or different in each unit p, or the alkylene group is unsaturated in which case two neighbouring X, or two neighbouring Y, or one neighbouring X and one neighbouring Y jointly represent a carbon-carbon double bond;n represents 3, 4, 5, 6, 7 or 8;x and y are selected independently from each other and either represent 0 or 1 with the proviso that the sum of x+y is either 1 or 2. Also provided are polymers obtained by the process, compositions and compounds containing the polymers and articles made from the compounds. Also provided are methods of making compounds and articles.